The present invention relates to an opening-force-maximizing device of an underpressure-activated, self-adjusting valve for a drinking container. The container may contain a pressurized or non-pressurized soft drink or other liquefied article of food. The device is intended for use in connection with a drinking spout for the container.
Underpressure-activated devices for automatic opening of drinking valves are known from previous patent publications, including U.S. Pat. No. 6,290,090. The opening mechanism according to U.S. Pat. No. 6,290,090 includes a pressure-responsive membrane for activating a valve of a drinking can containing a carbonated, pressurized drink. The valve allows for spill-free consumption of the contents of the can. The membrane, which forms a maneuvering member of the drinking valve, is concentric and formed approximately planar about the longitudinal axis of the drinking can, said plane being perpendicular to the longitudinal axis. The membrane is also fixedly attached along its entire circumference. A flow-through stay, which is a part of a sealing member of the valve, connects the membrane to the sealing member, which opens or closes an outlet opening of the can. The membrane is activated when a user sucks an underpressure on one side of it, thereby creating a differential pressure across the membrane. The differential pressure generates a pressure force moving the membrane and the sealing member in an axial and valve-opening direction. As the activating surface of the membrane is larger than the valve surface covering the outlet opening, a valve opening force is produced and transmitted, which may be sufficiently large for the valve to open, even at a given overpressure in the can.
To use this type of membrane structure for opening a valve of a drinking container of pressurized liquid, involves several weaknesses:
Inasmuch as the peripheral regions of the planar membrane according to U.S. Pat. No. 6,290,090 are secured and thereby may move insignificantly during said pressure influence, mainly the central portion of the membrane is axially moveable. The effective, pressure-responsive membrane surface area thus is reduced, causing relatively insignificant force to be transmitted to the valve sealing member. Increasing the area of the membrane in the radial direction may solve this problem. However, such a solution is not possible when used in standard bottle caps, in which the membrane diameter is limited by the cap diameter. The user may, however, compensate for a reduced, effective membrane area and attenuated pressure force by increasing the suction force on the membrane. However, the user must use a disproportionately large suction force, especially during incipient opening of the valve when the drinking can is pressurized. This valve device may not be perceived as being very functional and user-friendly.
Moreover, this membrane structure is not provided with bracing elements that concentrate and transmit the membrane pressure force to the valve sealing member.
Nor is the membrane structure arranged with any opening-force-maximizing device that limits the incipient suction force required during valve-opening of a pressurized drinking can.
The sealing member is also placed on the downstream side of the can's outlet opening, allowing it to open automatically at a given overpressure in the drinking can. Its liquid contents thus will flow out of the can unintentionally. If this unintended effect is to be avoided, the valve must only be used on drinking cans containing non-carbonated drinks, which defies the object of the valve device according to U.S. Pat. No. 6,290,090. Possibly, the membrane must be reinforced or braced to avoid unintended outflow when the liquid contents is pressurized, whereby the user must supply additional suction force to the membrane. However, this further weakens the functionality and user-friendliness of the valve.
In connection with ordinary bottle caps and carbonated drinks, the main problem of this membrane structure therefore lies in its effective membrane area being too small to provide sufficient valve opening force, especially in the opening phase of the valve. For this reason, the valve device according to U.S. Pat. No. 6,290,090 will be experienced as not being very functional and not being very user-friendly.